21261072 has 40 divisors (see below), whose sum is σ = 62771776. Its totient is φ = 6074496.

The previous prime is 21261059. The next prime is 21261077. The reversal of 21261072 is 27016212.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21261077) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31303 + ... + 31974.

Almost surely, 2^21261072 is an apocalyptic number.

It is an amenable number.

21261072 is an abundant number, since it is smaller than the sum of its proper divisors (41510704).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21261072 is a wasteful number, since it uses less digits than its factorization.

21261072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63295 (or 63289 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21261072 is about 4610.9729992703. The cubic root of 21261072 is about 277.0310104430.

Adding to 21261072 its reverse (27016212), we get a palindrome (48277284).

The spelling of 21261072 in words is "twenty-one million, two hundred sixty-one thousand, seventy-two".